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PPL > u6 > Flashcards

u6 Flashcards

1
Q

earths surface is heated unevenly because of…

A

rotation of earth, land and oceans, seasons

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2
Q

heat is moved around the earth via ________

A

water vapour

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3
Q

atmosphere is ___% nitrogen , ___% oxygen and ___% other

A

78% N
21% O
1% other

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4
Q

give layers of earth from land to space direction

A

troposphere, stratosphere, mesosphere, thermosphere, exosphere

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5
Q

what is the definition of “lapse rate”

A

how much the temperature changes over a given height

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6
Q

why does the tropopause shrink near poles but high near equator?

A

because equator = hot air rising expands it

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7
Q

lapse rate of troposphere

A

lose 2ºC of termerparte per 1000 ft height

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8
Q

the average temp of tropopause is _____ and the temp remains _______

A

-56ºC
isothermal (doesn’t change)

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9
Q

the stratosphere height in ft and km
lapse rate/temperature _______,
weather can’t penetrate further than this layer because of _________

A

180 000 ft
50 km
increases to 0º because of heated ozone layer
lack of convection

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10
Q

mesosphere height in ft and km
it has a ____ lapse rate
what type of molecules are found here

A

180 000 to 275 000 ft
50-80 km
positive (temp decreases with height)
light gases

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11
Q

thermosphere height starts at
____ lapse rate
why high temperatures?

A

100 km
negative (temp increases with altitude)
intense solar radiation

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12
Q

exosphere height
pressure is like a ________

A

500 km onward
vacuum

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13
Q

standard atmosphere (ISA)
pressure
temperate
pressure decrease per 1000 ft
termparteu decrease per 1000 ft
moisture?
rain?

A

29.92 inHg
15ºC
- 1 inHg drop per 1000 ft
- 2ºC drop per 1000 ft
dry air mass
no precipitation

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14
Q

what is station pressure
does a low or high altitude station have higher pressure

A

weight of the column of air extending upwards from station to atmosphere
low altitude because more air molecules within column

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15
Q

what is mean sea level (MSL) pressure

A

pressure of high altitude airport as if it was at sea level

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16
Q

what are isobars and why are they drawn on a map
they are drawn to be _____ hectopascals apart

A

connect locations of equal pressure
4 hectopascals

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17
Q

isobars close together = _____ pressure difference = _____ flow of air

A

large
fast

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18
Q

high pressure centre:
- air is ______
- flow/rotates:
- weather:

A

sinking
rotates clockwise and outward (anticyclone)
good weather

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19
Q

low pressure centre:
- air is ______
- flow/rotates:
- weather

A

rising
counter clockwise and inward (cyclone)
bad

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20
Q

what is a trough

A

elongated area of low pressure

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21
Q

what is a ridge

A

longed area of high pressure

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22
Q

what is a col

A

natural reaction between two highs and two lows

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23
Q

from high to low lookout below

what does that mean in terms of TEMP difference

A

temp decrease = air density increases and contracts = don’t need to fly as high to get same amount of lift = plane feels like its at xx height at lower true altitude

so flying from high to low temperature, plane will naturally descend because it feels like its at same altitude as before

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24
Q

from high to low lookout below

what does that mean in terms of PRESSURE difference

A

high pressure to low pressure = air density decreases

so staying at same true altitude, your altimeter will feel like you’re higher than you acc are in the low zone

obstacle clearance?

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25
Q

altimeter setting vs mean sea level (MSL) pressure

what do you use each for

A

altimeter setting = current atmospheric pressure reduced to sea level - for setting plane altimeter

MSL pressure = average pressure reduced to sea level over a period of 12h - for flight planning and weather purposes

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26
Q

colder than standard temperature puts the plane _____ than the altimeter says

A

lower

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27
Q

for every ___ºC temperature change, we change density altitude by 1000 ft

A

8ºC

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28
Q

heating of the atmosphere by

A

radiation and conduction

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29
Q

heating of the atmosphere by

A

radiation and conduction

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30
Q

variations in heating: diurnal variation, seasonal variation, latitude and topography

A

diurnal variation - day (convection currents rise/mixing atmosphere). night (cooling)

seasonal variation - earth tilt = different heating throughout year

latitude = most heating at equator

topography = land heats up faster than water

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31
Q

variations in heating: diurnal variation, seasonal variation, latitude and topography

A

diurnal variation - day (convection currents rise/mixing atmosphere). night (cooling)

seasonal variation - earth tilt = different heating throughout year

latitude = most heating at equator

topography = land heats up faster than water

32
Q

3 ways heat is moved around through the atmosphere

A

conduction
convection
advection

33
Q

how does compression of air molecules make the surrounding air warmer

A

when a large parcel of air sinks, its compressed by the increasing air pressure of the lower atmosphere

increased pressure = the air warms up

34
Q

3 ways the atmosphere cools

A

(lack of) radiation = surface cools
advection
adiabatic cooling

35
Q

dry adiabatic rate

A

3º per 1000 ft

36
Q

saturated adiabatic rate

A

1.5º per 1000 ft

37
Q

what is a temperature inversion, what causes it and is it stable?

A

when the temperature increases with altitude
caused by radiation cooling from the surface at night
stable

38
Q

what is an isotherm on a map

A

join places of equal temperature on map

39
Q

the amount of water vapour that air can hold is controlled by the air’s _____

A

temperature

40
Q

what is the dew point

A

termperature at a given pressure that the air must be COOLED to in order to reach 100% saturation

tells us how much water the atmosphere is currently holding

41
Q

cold or hot air holds more moisture and why

A

hot because more space for water molecules to fit

42
Q

what is the relative humidity (%)

A

the amount of water vapour present in the air compared to the amount that this air can hold when its saturated

43
Q

dry vs saturated air has ____% relative humidity

A

dry air = 0% relative humidity
saturated air = 100% relative humidity

44
Q

cooling or adding moisture will ______ relative humidity

A

increase

45
Q

standard vs environmental lapse rate difference

A

both are the rate that the temperature changes as altitude increases but standard is theoretical (2º/1000) whereas environmental is measured and changes daily

46
Q

frontal vs orographic vs conventional rainfall

A

frontal = two air masses/fronts converge

orographic = warm air forced over mountain and cools and rain

conventional = ground surface is locally heated so it rises cools and rain

47
Q

sleet/ice pellets vs freezing rain

A

ice pellets = snow drops into warm zone -> melts to rain -> drops in large cold zone -> freeze to ice

freezing rain = snow drops into warm zone -> melts to rain -> passes through a very shallow cold zone but doesn’t have time to completely re-freeze so it stays as rain

48
Q

sleet/ice pellets vs freezing rain

A

ice pellets = snow drops into warm zone -> melts to rain -> drops in large cold zone -> freeze to ice

freezing rain = snow drops into warm zone -> melts to rain -> passes through a very shallow cold zone but doesn’t have time to completely re-freeze so it stays as rain

49
Q

hail is frozen rain drops larger than _____

A

5 mm

50
Q

if the dew point is above freezing, _____ forms
if the dew point is below freezing, _____ forms

(dew vs frost)

A

dew
frost

51
Q

why does dew/frost form

A

on a moist day, if the ground cools the air will reach it’s saturation point and need to remove excess moisture

52
Q

why will a parcel of moist air rise faster than a parcel of dry air

A

moist air has a smaller adiabatic lapse rate than dry adiabatic lapse rate. so the difference between the environmental lapse rate and SALR is larger than ELR and DALR. since there’s a larger temperature difference with the moist air, it will rise quicker

53
Q

T/F: the atmosphere is unstable when the environment cools down faster than a parcel of air

A

true because the parcel of air will keep rising since the environment is colder than the parcel and the hot parcel will rise

54
Q

stable air:
____ flying
____ visibility
____ precipitation
_____ cloud
____ environment lapse rate
cause _____

A

smooth
poor
steady
layer/stratus
shallow
inversions

55
Q

what increases stable conditions

A

surface cooling
warming at higher altitudes

56
Q

unstable air
____ flying
____ visibility
____ precipitation
_____ cloud
____ environment lapse rate
can lead to _____

A

bumpy
good
showery
cumulus
steep
thunderstorm

57
Q

the greater the ELR, the more atmospheric ______

A

instability

58
Q

absolute stability

A

a parcel of air attempts to rise but will always be colder than the air surrounding it

DALR and SALR are steeper than ELR = air sunk

59
Q

conditional stability

A

stability depends on whether air is dry or saturated

only when the parcel of air is saturated it can rise

DALR is steeper (colder) than ELR = air sunk
SALR is shallower (warmer) than ELR = air rises

60
Q

absolute instability

A

parcel of air is always warmer than the outside temp so it always rises

DALR and SALR are shallower (warmer) than ELR = air rises

61
Q

potential instability

A

air is initially cold/stable and environment is warm so it’s not moving. whacky weather triggers at 5000 ft and all of a sudden the environment is extra cold so now the cold air parcel is under colder outside air so that air parcel rises

62
Q

what is solar wind

A

outermost particles of the sun escape the suns gravity and interacts with earth atmosphere -> northern lights

63
Q

what are sun spots

A

high energy zones on suns surface that appear dark

64
Q

what are solar flares

A

occurs when the sunspot releases huge amount of energy

65
Q

the earth’s tilt is ___º and the tilt is responsible for what

A

23.5º
changing seasons

66
Q

equinox vs solstices

A

equinox = day and night is the same length
solstices = day or night is the longest during the year

67
Q

what is light spreading

A

sunlight in the winter is spread over a large area because the sun passes through the atmosphere at a lower angle = less heat received by earth per square inch

68
Q

what is atmospheric scattering

A

as sun passes through atmosphere, particles of gas and dust scatter the light

most scattering near poles = less light directly hits surface
least scattering at equator because direct hit

69
Q

why is the north pole always cold

A
  • near winter, earth tilt makes it so that only a few hours of light a day
  • more light spreading
  • more atmospheric scattering
70
Q

“SKC”

A

sky clear

71
Q

FEW clouds

A

1/8 to 2/8 sky covered

72
Q

SCT clouds cover

A

3/8 to 4/8 of sky

73
Q

BKN clouds cover

A

5/8 to 7/8 of sky

74
Q

ceilings exist when sky is _____ or _____

A

BKN or OVC

75
Q

lenticular clouds

A
  • from mountain waves
  • flat
  • top of mountain wave: air rises = cold = condense int
76
Q

rotor clouds
- formed by _____
- air is _____

A

mountain waves
violent/turbulent

77
Q

a cap cloud forms over the top of the mountain and extends partially down the leeward slopes. this indicates…

A

a strong downdraft

PPL (14 decks)

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